The overall goal is to describe the respiratory-related efferent activities of the hypoglossal and trigeminal nerves. These activities and those of muscles which they innervate in the oropharyngeal region have been shown to be important for maintaining upper airway patency, especially in sleep. Alterations in these neural or muscular activities or those of single hypoglossal and trigeminal neurons will be characterized in response to changes in chemoreceptor stimuli or elicitation of upper airway and/or pulmonary reflexes. Changes in these activities will also be analyzed following administration of pharmacological substances which differentially alter activities of the hypoglossal and trigeminal systems as compared to the bulbospinalphrenic system. It is hypothesized that these differential actions reflect a greater dependency for activites of hypoglossal and trigeminal neurons than bulbospinal neurons upon reticular formation processes. Data obtained will provide significant insights into mechanisms required for maintenance of upper airway patency. These data may have direct and immediate applications to the diagnosis and treatment of obstructive apneas in adults and children.